Carbon and Hydrogen Isotopic Effects in Microbial, Methane from Terrestrial Environments

Chanton, Jeffrey P.; Chaser, Lia; Glasser, Paul H.; Siegel, D. I.

doi:10.1016/b978-012088447-6/50006-4

Cited by 75 publications

(116 citation statements)

References 61 publications

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“…Accordingly, the two precursors of methane, namely acetate and CO2/H2, yield methane with markedly different δ 13 C values; methane from acetate is relatively enriched in 13 C. Average minimum in the carbon isotopic composition of CH4 (-61.4 ‰) occurred deeper in sediments (60 cm) while average maximum in δ 13 C-CH4 occured in the lower sediment depth of 30 cm. Enrichment of 13 C in CH4 probably reflects aerobic CH4 oxidation because oxidation would result in residual CH4 with δ 13 C-CH4 values less negative than the source CH4 (Barker & Fritz 1981;Chanton et al 2004). However, this effect has been observed only at the study site IV.…”

Section: Stable Carbon Isotopesmentioning

confidence: 99%

Methanogenic System of a Small Lowland Stream Sitka, Czech Republic

Rulk¹,

Bednak²,

Mach³

et al. 2013

Biomass Now - Cultivation and Utilization

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Section: Stable Carbon Isotopesmentioning

confidence: 99%

Methanogenic System of a Small Lowland Stream Sitka, Czech Republic

Rulk¹,

Bednak²,

Mach³

et al. 2013

Biomass Now - Cultivation and Utilization

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“…It has been reported that anaerobic microbial CH 4 oxidation results in more positive δ 2 H-CH 4 and δ 13 C-CH 4 values, due to preferential uptake of the lighter isotopes 12 C and 1 H by methanotrophs (Chanton et al, 2004;Coleman et al, 1981;Whiticar, 1999). In this study, the molecular DNA analysis did not detect the presence of CH 4 oxidizing archaea and the cultures had very negative δ 2 H-CH 4 .…”

Section: Microbial Ch 4 Oxidationmentioning

confidence: 52%

“…There are two possible explanations for the unusually positive δ 13 C-CH 4 values observed in the cultures related to this study: substrate depletion effects (Whiticar, 1999) or microbial CH 4 oxidation that may result from methanogens that are operating in reverse (Chanton et al, 2004). Figure 5.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…Small isotopic fractionation factor α values (<1.055) are typical of the prevalent operation of acetoclastic methanogenesis, whereas higher α values (<1.065) are indicative of hydrogenotrophic methanogenesis (Whiticar et al, 1986). While these general ranges appear to be correct in most cases, the strict interpretation of CH 4 carbon isotopic data is not warranted (Chanton et al, 2004;Chidthaisong et al, 2002;Waldron et al, 1998;Whiticar, 1999). For example, high α values are typical of hydrogenotrophic methanogenesis, but in an environment with a high supply of free energy available to the methanogens, hydrogenotrophic methanogenesis may also cause a low α value (Conrad, 2005;Penning et al, 2005).…”

mentioning

confidence: 97%

“…In addition, CH 4 produced from H 2 +CO 2 is typically 13 C-depleted relative to that produced from acetate (Chanton et al, 2004;Conrad et al, 2011;Whiticar, 1999). Hydrogenotrophic methanogenesis derived CH 4 typically has δ 13 C-CH 4 between -110 ‰ and -60 ‰, while acetoclastic methanogenesis produced CH 4 has δ 13 C between -60 ‰ and -45 ‰ (Conrad et al, 2011;Whiticar, 1999).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Susilawati

Golding

Baublys

et al. 2016

International Journal of Coal Geology

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Carbon and hydrogen isotope compositions of CH 4 generated via methanogenesis in cultures of South Sumatra Basin (SSB) coalbed methane (CBM) formation waters grown on coal, acetate and H 2 +CO 2 were investigated. CH 4 production and molecular analysis confirmed the presence of active microbial communities that are able to convert coal into CH 4 using both acetoclastic and hydrogenotrophic pathways. The representative bacterial sequences were dominated by Bacteroidetes, Firmicutes and Deltaproteobacteria, while Methanosaeta and Methanosarcina were the most prevalent archaeal methanogens present in the cultures.CH 4 produced in this study's culturing experiments has δ 13 C values in the range of -50 ‰ to -20 ‰, with most values falling outside the current understanding of the carbon isotopic boundaries for biogenic CH 4 (-110 ‰ to -30 ‰). However, the corresponding apparent carbon isotopic α factor (α c = 1.02±0.006), and isotopic effect (ε c = -20.1 ‰ ±15.3) showed that CH 4 in SSB cultures was predominantly produced by acetoclastic methanogenesis, which is consistent with the results of molecular DNA analysis. In addition, the calculated contribution of CO 2 reduction from the δ 13 C values of coaltreated cultures was overall < 50 %, further confirming the high contribution of the acetoclastic pathway to CH 4 production in the SSB cultures. The outcome of this experimental study also suggests that δ 2 H-CH 4 values may not provide a reliable basis for distinguishing methanogenic pathways, while apparent carbon isotopic fractionation factor (α c ) and isotope effect (ε c ) are considered more useful indicators of the methanogenic pathway.The high δ 13 C-CH 4 values (>-30 ‰) and the dominance of Methanosaeta over Methanosarcina indicate that methanogens within the SSB cultures were operating at low substrate concentrations. An unusually positive δ 13 C-CH 4 suggests a substrate depletion effect, which is thought to be related to a decrease in the relative abundance of key bacterial coal degraders with formation water inoculum storage time. Closer observation of δ 13 C-CH 4 values during the growth of cultures within a single experiment also showed a 13 C-enrichment trend over time. At log phase of growth, the CH 4 produced was 13 C-depleted when compared to the stationary phase that also indicates substrate depletion effects. Finally, the δ 13 C-CH 4 values encountered in this study (as high as -20 ‰) highlight the possible positive extension of δ 13 C-CH 4 values of acetoclastic methanogenesis from those currently reported in the literature for natural and experimental samples (as high as -30 ‰).Keywords: Biogenic gas, coal, culture experiment, isotopic composition INTRODUCTIONArchaeal methanogens are the only known microorganisms capable of forming CH 4 . These strictly anaerobic microbes are restricted to utilizing simple compounds that contain no more than two carbon atoms. As such, complex organic compounds in anoxic environments (e.g., marine sediments, rice paddies, subsurface shales and coalbeds) ...

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Carbon dioxide and methane emissions from an artificially drained coastal wetland during a flood: Implications for wetland global warming potential

Gatland

Santos

Maher

et al. 2014

J. Geophys. Res. Biogeosci.

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Floods frequently produce deoxygenation and acidification in waters of artificially drained coastal acid sulfate soil (CASS) wetlands. These conditions are ideal for carbon dioxide and methane production. We investigated CO 2 and CH 4 dynamics and quantified carbon loss within an artificially drained CASS wetland during and after a flood. We separated the system into wetland soils (inundated soil during flood and exposed soil during post flood period), drain water, and creek water and performed measurements of free CO 2 ([CO 2 *]), CH 4 , dissolved inorganic and organic carbon (DIC and DOC), stable carbon isotopes, and radon ( 222 Rn: natural tracer for groundwater discharge) to determine aquatic carbon loss pathways. [CO 2 *] and CH 4 values in the creek reached 721 and 81 μM, respectively, 2 weeks following a flood during a severe deoxygenation phase (dissolved oxygen~0% saturation). CO 2 and CH 4 emissions from the floodplain to the atmosphere were 17-fold and 170-fold higher during the flooded period compared to the post-flood period, respectively. CO 2 emissions accounted for about 90% of total floodplain mass carbon losses during both the flooded and post-flood periods. Assuming a 20 and 100 year global warming potential (GWP) for CH 4 of 105 and 27 CO 2 -equivalents, CH 4 emission contributed to 85% and 60% of total floodplain CO 2-equivalent emissions, respectively. Stable carbon isotopes (δ 13 C in dissolved CO 2 and CH 4 ) and 222 Rn indicated that carbon dynamics within the creek were more likely driven by drainage of surface floodwaters from the CASS wetland rather than groundwater seepage. This study demonstrated that >90% of CO 2 and CH 4 emissions from the wetland system occurred during the flood period and that the inundated wetland was responsible for~95% of CO 2 -equivalent emissions over the floodplain.

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Carbon and Hydrogen Isotopic Effects in Microbial, Methane from Terrestrial Environments

Cited by 75 publications

References 61 publications

Methanogenic System of a Small Lowland Stream Sitka, Czech Republic

Methanogenic System of a Small Lowland Stream Sitka, Czech Republic

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Carbon dioxide and methane emissions from an artificially drained coastal wetland during a flood: Implications for wetland global warming potential

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